From b2b89f55dfe3f19c8028d6c907d1ab53766b534b Mon Sep 17 00:00:00 2001 From: Rodrigo Vivi Date: Fri, 14 Nov 2014 08:52:29 -0800 Subject: [PATCH] drm/i915: Add PSR docbook Let's document PSR a bit. No functional changes. v2: Add actual DocBook entry and accept Daniel's improvements. Cc: Daniel Vetter Signed-off-by: Rodrigo Vivi Signed-off-by: Daniel Vetter --- Documentation/DocBook/drm.tmpl | 5 +++ drivers/gpu/drm/i915/intel_psr.c | 73 ++++++++++++++++++++++++++++++++ 2 files changed, 78 insertions(+) diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index 9449cd65f1d0..a1168a8e2279 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -3891,6 +3891,11 @@ int num_ioctls; High Definition Audio !Pdrivers/gpu/drm/i915/intel_audio.c High Definition Audio over HDMI and Display Port !Idrivers/gpu/drm/i915/intel_audio.c + + + Panel Self Refresh PSR (PSR/SRD) +!Pdrivers/gpu/drm/i915/intel_psr.c Panel Self Refresh (PSR/SRD) +!Idrivers/gpu/drm/i915/intel_psr.c DPIO diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c index 7b3ed910bc48..716b8a961eea 100644 --- a/drivers/gpu/drm/i915/intel_psr.c +++ b/drivers/gpu/drm/i915/intel_psr.c @@ -21,6 +21,36 @@ * DEALINGS IN THE SOFTWARE. */ +/** + * DOC: Panel Self Refresh (PSR/SRD) + * + * Since Haswell Display controller supports Panel Self-Refresh on display + * panels witch have a remote frame buffer (RFB) implemented according to PSR + * spec in eDP1.3. PSR feature allows the display to go to lower standby states + * when system is idle but display is on as it eliminates display refresh + * request to DDR memory completely as long as the frame buffer for that + * display is unchanged. + * + * Panel Self Refresh must be supported by both Hardware (source) and + * Panel (sink). + * + * PSR saves power by caching the framebuffer in the panel RFB, which allows us + * to power down the link and memory controller. For DSI panels the same idea + * is called "manual mode". + * + * The implementation uses the hardware-based PSR support which automatically + * enters/exits self-refresh mode. The hardware takes care of sending the + * required DP aux message and could even retrain the link (that part isn't + * enabled yet though). The hardware also keeps track of any frontbuffer + * changes to know when to exit self-refresh mode again. Unfortunately that + * part doesn't work too well, hence why the i915 PSR support uses the + * software frontbuffer tracking to make sure it doesn't miss a screen + * update. For this integration intel_psr_invalidate() and intel_psr_flush() + * get called by the frontbuffer tracking code. Note that because of locking + * issues the self-refresh re-enable code is done from a work queue, which + * must be correctly synchronized/cancelled when shutting down the pipe." + */ + #include #include "intel_drv.h" @@ -217,6 +247,12 @@ static void intel_psr_do_enable(struct intel_dp *intel_dp) dev_priv->psr.active = true; } +/** + * intel_psr_enable - Enable PSR + * @intel_dp: Intel DP + * + * This function can only be called after the pipe is fully trained and enabled. + */ void intel_psr_enable(struct intel_dp *intel_dp) { struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp); @@ -258,6 +294,12 @@ unlock: mutex_unlock(&dev_priv->psr.lock); } +/** + * intel_psr_disable - Disable PSR + * @intel_dp: Intel DP + * + * This function needs to be called before disabling pipe. + */ void intel_psr_disable(struct intel_dp *intel_dp) { struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp); @@ -342,6 +384,18 @@ static void intel_psr_exit(struct drm_device *dev) } +/** + * intel_psr_invalidate - Invalidade PSR + * @dev: DRM device + * @frontbuffer_bits: frontbuffer plane tracking bits + * + * Since the hardware frontbuffer tracking has gaps we need to integrate + * with the software frontbuffer tracking. This function gets called every + * time frontbuffer rendering starts and a buffer gets dirtied. PSR must be + * disabled if the frontbuffer mask contains a buffer relevant to PSR. + * + * Dirty frontbuffers relevant to PSR are tracked in busy_frontbuffer_bits." + */ void intel_psr_invalidate(struct drm_device *dev, unsigned frontbuffer_bits) { @@ -366,6 +420,18 @@ void intel_psr_invalidate(struct drm_device *dev, mutex_unlock(&dev_priv->psr.lock); } +/** + * intel_psr_flush - Flush PSR + * @dev: DRM device + * @frontbuffer_bits: frontbuffer plane tracking bits + * + * Since the hardware frontbuffer tracking has gaps we need to integrate + * with the software frontbuffer tracking. This function gets called every + * time frontbuffer rendering has completed and flushed out to memory. PSR + * can be enabled again if no other frontbuffer relevant to PSR is dirty. + * + * Dirty frontbuffers relevant to PSR are tracked in busy_frontbuffer_bits. + */ void intel_psr_flush(struct drm_device *dev, unsigned frontbuffer_bits) { @@ -399,6 +465,13 @@ void intel_psr_flush(struct drm_device *dev, mutex_unlock(&dev_priv->psr.lock); } +/** + * intel_psr_init - Init basic PSR work and mutex. + * @dev: DRM device + * + * This function is called only once at driver load to initialize basic + * PSR stuff. + */ void intel_psr_init(struct drm_device *dev) { struct drm_i915_private *dev_priv = dev->dev_private; -- 2.20.1